1. Field of the Invention
The present invention relates to a plasma processing apparatus.
2. Description of the Related Art
Techniques are known for controlling the generation of plasma in a plasma processing apparatus that supplies a gas into a chamber, generates plasma from the gas using a high frequency power, and performs a predetermined plasma process on a substrate that is held by a mounting table.
For example, Japanese Laid-Open Patent Publication No. 2001-185542 (Patent Document 1) discloses an apparatus including a current path correction means for correcting a part of a high frequency current path that is formed by a high frequency bias applied to a wafer and is near an outer periphery of the wafer, wherein the current path part is forced toward an opposing electrode surface facing the wafer. As an example of the current path correction means, a conductive member is disposed near a wall at a lower part of a dielectric body.
However, according to Patent Document 1, the conductive member is configured to correct a current path in order to control a plasma generation region within the chamber and improve plasma processing in-plane uniformity of a wafer. On the other hand, Patent Document 1 does not contemplate measures for suppressing the occurrence of abnormal discharge within the chamber.
When abnormal discharge occurs within the chamber, the chamber may be damaged and particles may be generated from the chamber walls. The particles may be dispersed on a wafer while a plasma process is performed thereon, and short-circuits may occur in the wirings formed on the wafer, for example.